Fuel system for a multi-fuel internal combustion engine

ABSTRACT

A multi-fuel engine includes an engine operable on a liquid fuel and first and second gaseous fuels. The multi-fuel engine also includes a liquid cutoff solenoid selectively operable between open and closed positions to allow and inhibit a flow of the liquid fuel to the engine and at least one gaseous cutoff valve selectively operable between open and closed positions to allow and inhibit a flow of the first and second gaseous fuels to the engine. A jet block couples the first gaseous fuel source and the second gaseous fuel source to a carburetor connected to an intake of the engine, with the jet block being located downstream from the at least one gaseous cutoff valve. The jet block includes a first gaseous fuel jet to meter the first gaseous fuel to the carburetor and a second gaseous fuel jet to meter the second gaseous fuel to the carburetor.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of and claims priority to U.S.patent application Ser. No. 16/358,822, filed Mar. 20, 2019, which is acontinuation of and claims priority to U.S. patent application Ser. No.15/285,215, filed Oct. 4, 2016, now Issued U.S. Pat. No. 10,393,034,which is a continuation-in-part of and claims priority to U.S. patentapplication Ser. No. 14/925,441, filed Oct. 28, 2015, which is acontinuation-in-part of and claims priority to U.S. patent applicationSer. No. 14/738,060, filed Jun. 12, 2015, now Issued U.S. Pat. No.10,221,780, the disclosures of which are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

Embodiments of the invention relate generally to dual fuel and othermulti-fuel internal combustion engines, and more particularly, to anapparatus and method for delivering liquid fuel and gaseous fuel to agenerator driven by a multi-fuel internal combustion engine.

Electric generators are frequently driven by internal combustion enginesthat use gasoline as a fuel source. Gasoline is a common fuel source forgenerators in a variety of applications. However, alternative fuelsources also provide a desirable fuel source. For instance, alternativefuels may provide a cleaner burning fuel that limits undesirableemissions. Alternative fuels may also be stored for longer periods oftime without degradation, whereas gasoline can degrade over a period ofmonths leading to hard starting, rough running, and also lead to gum andvarnish deposits in the fuel system. In addition, generators thatoperate on alternative fuels are able to generate electricity whengasoline is not readily available. For instance, generators arefrequently used when power outages in the utility grid result fromsevere weather. Unfortunately, gas stations may also be closed as aresult of the power outage. Such a circumstance presents just oneexample where it would be advantageous to operate electric generators onalternative fuels.

Certain generators are configured to operate as “dual fuel” generators,otherwise known as bi-fuel generators. These generators are driven by aninternal combustion engine that is configured to operate on eitherliquid fuel or an alternative fuel. The alternative fuel may exist in agaseous state at normal temperature and pressure and can be any one ofliquefied petroleum gas, compressed natural gas, hydrogen, or the like.Liquefied petroleum gas (LPG), often referred to as propane, exists in agaseous state at normal temperature and pressure but can be convenientlystored under pressure in a liquid state. LPG may be a desirable fuelsource for internal combustion engines because it can be stored forextended periods of time and contains fewer impurities than gasoline,resulting in smoother and cleaner operation. In addition, propane fueledengines typically have a longer life cycle due to less carbon build-upand virtually no fuel gumming or varnish accumulation.

In order to provide the liquid and gaseous fuel to the engine, the dualfuel engine may have a first fuel line for liquid fuel and a second fuelline for gaseous fuel. A liquid fuel source and a gaseous fuel sourcemay be coupled to the respective lines to provide fuel to the engine.However, a common problem with such configurations that couple two fuelsources to a single fuel inlet, such as a carburetor, of an engine isthat during cross-over switching between the fuel sources the engine canexperience overly rich air-fuel ratio. This is particularly problematicwhen switching from a liquid fuel to a gaseous fuel because carburetorshave a fuel bowl containing fuel that is drawn into the engine evenafter the liquid fuel source is cut-off. Therefore, for a period oftime, the engine is running on both liquid and gaseous fuels causing anoverly rich fuel mixture. Further, such simultaneous delivery of fuelfrom the first fuel line and the second fuel line, even if for a brieftime, may make the engine hard to start and lead to unstable operatingconditions.

Therefore, it would be desirable to design a generator having a liquidfuel and gaseous fuel delivery system that overcomes the aforementioneddetriments without substantially increasing the overall cost of thesystem.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with one aspect of the invention, a multi-fuel engineincludes an engine operable on a liquid fuel, a first gaseous fuel froma first gaseous fuel source, and a second gaseous fuel from a secondgaseous fuel source. The multi-fuel engine also includes a liquid cutoffsolenoid coupled to open and close a liquid fuel path to the engine, afirst gaseous cutoff solenoid coupled to open and close the firstgaseous fuel source to the engine, a second gaseous cutoff solenoidcoupling the engine to the second gaseous fuel source to control flow ofthe second gaseous fuel to the engine, and a switch coupling a powersource to the liquid cutoff solenoid and the first gaseous cutoffsolenoid to switch between fuel sources on-the-fly during engineoperation.

In accordance with another aspect of the invention, a multi-fuel engineincludes an engine operable on a liquid fuel, a first gaseous fuel froma first gaseous fuel source, and a second gaseous fuel from a secondgaseous fuel source. The multi-fuel engine also includes a liquid cutoffsolenoid selectively operable between open and closed positions to allowand inhibit a flow of the liquid fuel to the engine, at least onegaseous cutoff valve selectively operable between open and closedpositions to allow and inhibit a flow of the first gaseous fuel and thesecond gaseous fuel to the engine. and a jet block coupling the firstgaseous fuel source and the second gaseous fuel source to a carburetorconnected to an intake of the engine, wherein the jet block is locateddownstream from the at least one gaseous cutoff valve. The jet blockfurther includes a first gaseous fuel jet configured to meter the firstgaseous fuel to the carburetor and a second gaseous fuel jet configuredto meter the second gaseous fuel to the carburetor.

Various other features and advantages will be made apparent from thefollowing detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate preferred embodiments presently contemplated forcarrying out the invention.

In the drawings:

FIG. 1 is a perspective view of a multi-fuel generator coupled to a fueldelivery system, according to an embodiment of the invention.

FIG. 2 is a schematic diagram of a fuel system for the multi-fuelgenerator of FIG. 1 configured in a bi-fuel arrangement, according to anembodiment of the invention.

FIG. 3 is a schematic diagram of a fuel system for the multi-fuelgenerator of FIG. 1 to operate in a tri-fuel arrangement, according toan embodiment of the invention.

FIG. 4 is a cross-sectional view of a carburetor for the multi-fuelgenerator of FIG. 1 taken transverse to a throat of the carburetor andthrough a fuel passage that provides fuel from a float bowl to thethroat of the carburetor, according to an embodiment of the invention.

FIG. 5 is a cross-sectional view of the carburetor of FIG. 4 coupled toan engine intake taken lengthwise to the throat and through the fuelpassage, according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The operating environment of the invention is described with respect toa multi-fuel generator. However, it will be appreciated by those skilledin the art that the invention is equally applicable for use with anymulti-fuel internal combustion engine. Moreover, the invention will bedescribed with respect to a dual fuel or other multi-fuel generatorconfigured to operate on liquid fuel and gaseous fuel. However, oneskilled in the art will further appreciate that the invention is equallyapplicable for use with other fuel combinations for multi-fuelgenerators and internal combustion engines.

Referring to FIG. 1, a dual fuel generator 30 is coupled to fueldelivery systems 32, 33 in accordance with an embodiment of theinvention. Dual fuel generator 30 includes a dual fuel internalcombustion engine 34 within housing 36 at one end 38, operativelyconnected to an alternator 40 also enclosed in housing 36 at another end42 by conventional means. Dual fuel generator 30 is configured tooperate on different fuels via either a first fuel source 44 or a secondfuel source 46. In an exemplary embodiment of the invention, first fuelsource 44 is a liquid fuel and second fuel source 46 is a gaseous fuel.In one preferred embodiment, the liquid fuel is gasoline and the gaseousfuel is liquid petroleum gas (LPG). An operator can selectively operatethe generator on either fuel as desired. For instance, generator 30 mayoperate on gasoline for a first period of operation and then switch toLPG for a second period of operation. However, it is contemplated thatdual fuel generator 30 is configured to operate on fuels other thangasoline and LPG (e.g., natural gas, biodiesel, etc.), and thus thescope of the invention is not meant to be limited strictly to a dualfuel arrangement where first fuel source 44 provides gasoline and secondfuel source 46 provides LPG. In addition, embodiments of the inventioncontemplate tri-fuel, quad-fuel, and other multi-fuel arrangements.

In one embodiment of the invention, dual fuel generator 30 includes agasoline tank 48 or, generally, a liquid fuel tank, located inside cover36 onboard generator 30 to provide gasoline to the engine as first fuelsource 44. Gasoline tank 48 connects to a first fuel line to providegasoline to the carburetor to run the engine, as will later be describedwith reference to FIG. 2. Generator 30 is also coupled to a pressurizedfuel container 50, or a pressurized fuel source, located off boardgenerator 30 to provide LPG to the engine as second fuel source 46.Pressurized fuel container 50 is coupled to generator 30 with an LPGsupply hose 52. LPG supply hose 52 is coupled to a second fuel linewithin generator 30 to provide LPG to the engine via the carburetor.Dual fuel generator 30 includes an electrical fuel switch 54 forselecting a desired fuel to the engine.

In an exemplary embodiment, fuel 46 from pressurized fuel container 50is regulated using a fuel regulator system 56 for delivery to theengine. Fuel regulator system 56 includes one or more pressureregulators that reduce and control the pressure of the fuel frompressurized fuel container 50 and delivers fuel at a desired pressurefor operation of the engine. Fuel regulator system 56 has an inlet 58operatively coupled to a service valve 60 of pressurized fuel container50 and an outlet 62 coupled to LPG supply hose 52. Fuel regulator system56 includes a primary pressure regulator 64 coupled to pressurized fuelcontainer 50 and a secondary pressure regulator 66. Primary pressureregulator 64 protects downstream components from high pressure ofpressurized fuel container 50. Primary pressure regulator 64 receivesLPG through service valve 60 of pressurized fuel container 50 andreduces the pressure of the LPG to a first stage. In one embodiment ofthe invention, the first stage may be delivered directly to generator 30at a pressure required for operation of the engine.

In an exemplary embodiment of the invention, fuel regulator system 56includes secondary pressure regulator 66 coupled to the outlet ofprimary pressure regulator 64 in order to use standard “off-the-shelf”components. Typically, the primary pressure regulator is mounted on theLPG tank, while the secondary pressure regulator is mounted on thecomponent using the fuel, such as an engine or grill. Here, sincegenerator 30 can be used as a gasoline only generator, secondarypressure regulator 66 is mounted off-board the generator to reduce sizeand cost of the generator. Secondary pressure regulator 66 receives LPGfrom primary pressure regulator 64 and further reduces the pressure ofLPG to a second stage to be delivered to generator 30. In a system withtwo regulators, primary pressure regulator 64 regulates fuel receivedfrom pressurized fuel container 50 and reduces the pressure of the fuelto a level required for operation of secondary pressure regulator 66.Secondary pressure regulator 66 regulates fuel received from primarypressure regulator 64 and further reduces the pressure of the fuel to alevel required for operation of generator 30. In addition, primarypressure regulator 64 may compensate for varying tank pressure as fuelis depleted while secondary pressure regulator 66 may compensate forvarying demand from generator 30.

In accordance with an exemplary embodiment of the invention, fuelregulator system 56 includes both the primary and secondary regulatorsor a customized single regulator to perform both regulator functions inone, but in any case, in this embodiment, is located remotely, oroff-board, from dual fuel generator 30. Fuel regulator system 56 may bedirectly mounted to pressurized fuel container 50 using a regulatormounting structure 68. Regulator mounting structure 68 is a devicehaving mounting locations for primary pressure regulator 64 andsecondary pressure regulator 66. Regulator mounting structure 68 alsohas a securing mechanism 70 to secure regulator mounting structure 68 topressurized fuel container 50. The securing mechanism 70 is a cover ordome that sits on the container with an opening therein that fits aroundservice valve 60.

In another embodiment of the invention, primary pressure regulator 64 ismounted on regulator mounting structure 68 while secondary pressureregulator 66 could be mounted on or near generator 30. In yet anotherembodiment of the invention, a dual stage regulator regulates the fuelreceived from pressurized fuel container 50 and delivers fuel at apressure required for operation of generator 30. Such a dual stageregulator regulates the fuel to the second stage within a singlestructure and may comprise both the primary pressure regulator 64 andthe secondary pressure regulator 66. The dual stage regulator may bemounted directly on fuel container 50. Pressurized fuel container 50 maybe secured to a platform or mobile cart 72 for stability ortransportation. In another embodiment, a regulator mounting structure 68is secured directly to a platform or a mobile cart.

A quick-disconnect hose coupling 74, also referred to as a quick-connecthose coupling, connects LPG supply hose 52 to generator 30 so that LPGsupply hose 52 may be quickly attached and detached from generator 30.Hose coupling 74 has a first end 74 a mounted on the external surface ofgenerator 30 and coupled to supply the second fuel to the engine. Hosecoupling 74 has a second end 74 b coupled to the outlet of LPG supplyhose 52. Hose coupling 74 has a valve that opens when the couplings areengaged and closes when the couplings are disengaged. As such,quick-disconnect hose coupling 74 automatically opens when connected toenable fuel flow from LPG supply hose 52 to the engine. Hose coupling 74automatically disconnects fluid communication when disconnected.Accordingly, when the supply hose is detached from generator 30, thecoupling 74 is automatically closed so that fuel does not escape andunwanted air does not enter the fuel system.

Referring now to FIG. 2, a schematic diagram of a fuel system for thedual fuel generator is shown, in accordance with an embodiment of theinvention. The fuel system includes an electro-mechanical valve system76 that includes a carburetor cutoff solenoid 94, gasoline cutoffsolenoid 96, and a LPG cutoff solenoid 98. The electro-mechanical valvesystem 76 is coupled to a multi-fuel internal combustion engineconfigured to operate on a liquid fuel supplied from a liquid fuelsource 78 through a liquid fuel line 80, and a gaseous fuel suppliedfrom a gaseous fuel source 82, or a pressurized fuel source, through agaseous fuel line 84. Electro-mechanical valve system 76 is operated byelectrical fuel switch 54 that controls fuel flow to the engine fromliquid fuel source 78 and gaseous fuel source 82. In an exemplaryembodiment of the invention, the dual fuel engine operates on gasolinefrom liquid fuel source 78 and LPG from gaseous fuel source 82.

In one embodiment of the invention, the engine has a carburetor 86coupled to an intake of the engine to mix air and fuel and connect toliquid fuel line 80 and gaseous fuel line 84. Carburetor 86 has a mixingpassage or throat with an inlet for air and an outlet for the air-fuelmixture. Carburetor 86 also has a float bowl 88 that receives liquidfuel through a liquid fuel inlet 90 coupled to liquid fuel line 80.Carburetor 86 may also have a gaseous fuel inlet 92 in the throat andcoupled to gaseous fuel line 84. Gaseous fuel inlet 92 is preferablylocated upstream from a venturi in the throat for improved fuel and airmixing. Air is mixed with either of the fuels in the throat to providethe air-fuel mixture for operation of the engine. In another embodimentof the invention, a gaseous fuel mixer couples to the engine intake tomix gaseous fuel and air separately from carburetor 86.

In an exemplary embodiment of the invention, electro-mechanical valvesystem 76 includes a carburetor cutoff solenoid 94 coupled to carburetor86 to control liquid fuel flow to the engine. Carburetor cutoff solenoid94 operates to open and close a liquid fuel path to the enginedownstream from float bowl 88 in carburetor 86. The liquid fuel path incarburetor 86 provides fuel to the throat from float bowl 88 and willlater be described with reference to FIG. 4. The liquid fuel path maycomprise a main fuel circuit within carburetor 86, and in some cases,also includes an idle fuel circuit within carburetor 86. Carburetorcutoff solenoid 94 cuts off liquid fuel flow through the liquid fuelpath to provide a liquid fuel cutoff solenoid that controls fuel flowfrom liquid fuel line 80 to the engine.

Electro-mechanical valve system 76 may include a gasoline cutoffsolenoid 96, or generally a liquid fuel cutoff solenoid, coupling liquidfuel source 78 to carburetor 86 and to control flow of the liquid fuelto carburetor 86. That is, gasoline cutoff solenoid 96 provides a liquidfuel valve coupled along liquid fuel line 80 to open and close liquidfuel source 78 to the engine. Electro-mechanical valve system 76 canoperate with either or both the gasoline cutoff solenoid 96 andcarburetor cutoff solenoid 94 to control liquid fuel flow to the engine.However, gasoline cutoff solenoid 96 is advantageous to quickly cut-offall liquid fuel flow to carburetor 86, and particularly, through theidle fuel circuit if carburetor cutoff solenoid 94 is regulating fuelthrough the main fuel circuit only. While limited fuel flow through theidle fuel circuit may not noticeably affect gaseous fuel operation,gasoline cutoff solenoid 96 prevents drawing gasoline through the idlefuel circuit after carburetor cutoff solenoid 94 closes the main fuelcircuit.

Electro-mechanical valve system 76 may include an LPG cutoff solenoid98, or generally a gaseous fuel cutoff solenoid, coupling gaseous fuelsource 82 to the intake and to control flow of the gaseous fuel to theengine. LPG cutoff solenoid 98 provides a gaseous fuel valve coupledalong gaseous fuel line 84 to open and close gaseous fuel source 82 tothe engine. LPG cutoff solenoid 98 is preferably located downstream fromfuel regulator system 56, shown in FIG. 2 as dual stage regulator 100,for a fast response in controlling gaseous fuel delivery to the engine.

Electro-mechanical valve system 76 also includes electrical switch 54coupling a power source 102 to one or more of carburetor cutoff solenoid94, gasoline cutoff solenoid 96 and LPG cutoff solenoid 98 to actuatethe solenoids and provide a one-touch fuel selector to switch engineoperation between fuels. Power source 102 is shown as a battery in FIG.2, but could be from an engine driven power source, such as analternator 40 (FIG. 1), a magneto, or any other suitable power supply.Switch 54 selectively powers solenoids 94, 96, 98 to engage liquid fueloperation when actuated to a first position and gaseous fuel operationwhen actuated to a second position. In an exemplary embodiment of theinvention, switch 54 engages gasoline operation by closing LPG cutoffsolenoid 98, opening gasoline cutoff solenoid 96, and operatingcarburetor cutoff solenoid 94 to open the main fuel circuit in thecarburetor, and switch 54 engages LPG operation by closing gasolinecutoff solenoid 96, operating carburetor cutoff solenoid 94 to close themain fuel circuit, and opening LPG cutoff solenoid 98.

In an exemplary embodiment of the invention, gasoline cutoff solenoid96, LPG cutoff solenoid 98, and carburetor cutoff solenoid 94 operate asnormally closed solenoid valves to ensure excess fuel is not deliveredto the engine if power to the solenoids is interrupted. To engage LPGoperation, electrical fuel switch 54 provides electrical connectionbetween power source 102 and a first contact 104 to power LPG cutoffsolenoid 98 to open gaseous fuel line 84 while gasoline cutoff solenoid96 and carburetor cutoff solenoid 94 are unpowered to close liquid fuelline 80 and the main fuel circuit in carburetor 86, respectively. Toengage gasoline operation, electrical switch 54 provides electricalconnection between power source 102 and a second contact 106 to powergasoline cutoff solenoid 96 and carburetor cutoff solenoid 94 to openliquid fuel line 80 and the main fuel circuit in carburetor 86,respectively, while LPG cutoff solenoid 98 is unpowered to close gaseousfuel line 84.

In an alternative embodiment of the invention, gasoline cutoff solenoid96, LPG cutoff solenoid 98, and carburetor cutoff solenoid 94 operate asnormally open solenoid valves to ensure fuel is provided to the engineif power to the solenoids is interrupted. To engage gasoline operation,switch 54 provides electrical connection between power source 102 andfirst contact 104 to power LPG cutoff solenoid 98 to close gaseous fuelline 84 while gasoline cutoff solenoid 96 and carburetor cutoff solenoid94 are unpowered to open liquid fuel line 80 and the main fuel circuitin carburetor 86, respectively. To engage LPG operation, switch 54provides electrical connection between power source 102 and secondcontact 106 to power gasoline cutoff solenoid 96 and carburetor cutoffsolenoid 94 to close liquid fuel line 80 and the main fuel circuit incarburetor 86, respectively, while LPG cutoff solenoid 98 is unpoweredto open gaseous fuel line 84.

Electro-mechanical valve system 76 can be configured to switch operationof the generator from multiple fuel sources while the generator isrunning, also referred to as “on-the-fly” fuel changeover. That is,switch 54 couples power source 102 to LPG cutoff solenoid 98 and one ormore of the gasoline cutoff solenoid 96 and carburetor cutoff solenoid94 to change operation of the engine from liquid fuel to gaseous fueland from gaseous fuel to liquid fuel while the engine is running.Electro-mechanical valve system 76 provides for precisely timed fuelchangeover between the fuel sources to switch engine operation withminimal or no interruption in the performance of the engine, and it canbe timed to prevent or substantially prevent fuel overlap between thefuel sources.

To quickly start and stop liquid fuel delivery to the engine, carburetorcutoff solenoid 94 regulates fuel flow through a liquid fuel pathdownstream of float bowl 88. Carburetor cutoff solenoid 94 also trapsenough gasoline in float bowl 88 to provide quick delivery of gasolineto the engine during changeover from LPG to gasoline to prevent any lagor hesitation in engine performance. During changeover from gasoline toLPG, carburetor cutoff solenoid 94 blocks fuel flow from float bowl 88to the engine, thereby preventing an over-rich condition. That is,carburetor cutoff solenoid 94 can block gasoline remaining in float bowl88 after gasoline cutoff solenoid 96 closes liquid fuel line 80 toprevent mixing gasoline with the LPG. Accordingly, carburetor cutoffsolenoid 94 responds quickly upon actuation of switch 54 to limit fueloverlap and prevent overly rich fuel conditions that could adverselyaffect engine performance.

In addition, gasoline cutoff solenoid 96 may be opened to fill floatbowl 88 with liquid fuel prior to switching engine operation to liquidfuel. That is, float bowl 88 will empty through the idle fuel circuit ifcarburetor cutoff solenoid 94 only blocks the main fuel circuit.Gasoline delivery to the engine during changeover is delayed if floatbowl 88 must first be filled, and such delay could cause the engine tolose power or stall. Therefore, switch 54 may be configured to actuategasoline cutoff solenoid 96 prior to actuating carburetor cutoffsolenoid 94 to ensure adequate fuel in float bowl 88 for a smoothtransition from LPG to gasoline.

In one embodiment of the invention, switch 54 actuates carburetor cutoffsolenoid 94 and LPG cutoff solenoid 98 to change engine operationbetween the liquid fuel and the gaseous fuel so as to prevent fuel flowfrom liquid fuel source 78 and gaseous fuel source 82 simultaneously. Insuch an embodiment, electro-mechanical valve system 76 operates as adual fuel lockout to ensure only one fuel is delivered to the engine.Switch 54 may simultaneously actuate carburetor cutoff solenoid 94 andLPG cutoff solenoid 98 to prevent or substantially prevent simultaneousfuel delivery of the liquid fuel and the gaseous fuel to the engine. Inother embodiments, switch 54 actuates any of solenoids 94, 96, 98 insuccession to prevent or substantially prevent simultaneous fueldelivery of the liquid fuel and the gaseous fuel to the engine. As such,switch 54 can operate the electro-mechanical valve system 76 to preventan overly rich air-fuel ratio during cross-over switching between fuelsources, even while operating at full load.

In another embodiment of the invention, electro-mechanical valve system76 provides a slight overlap in fuel delivery to the engine to ensure asmooth transition during changeover. Carburetor cutoff solenoid 94 mayclose the liquid fuel path in carburetor 86 after LPG cutoff solenoid 98opens to ensure fuel flow to the engine is not interrupted duringchangeover from gasoline to LPG. LPG cutoff solenoid 98 may close aftercarburetor cutoff solenoid 94 opens the liquid fuel path in carburetor86 to ensure fuel flow to the engine is not interrupted duringchangeover from LPG to gasoline. Accordingly, switch 54 may actuate LPGcutoff solenoid 98 and carburetor cutoff solenoid 94 in succession toprovide fuel overlap when changing engine operation between the liquidfuel and the gaseous fuel. Electro-mechanical valve system 76 can alsobe configured to provide blended fuel operation, if so desired.

Switch 54 can institute a predefined delay between actuating any ofgasoline cutoff solenoid 96, carburetor cutoff solenoid 94, and LPGcutoff solenoid 98. Adjustable rheostats or predefined electronic delaycircuits 108, 110, 112 can be coupled to the electrical connections ofany of solenoids 94, 96, 98 to delay their actuation. As such, any ofsolenoids 96, 94, 98 may be configured to operate according to a useradjustable preset delay to actuate one or more of the solenoids insuccession. In some embodiments of the invention, electronic delaycircuits 108, 110, 112 provide simultaneous delivery of fuels to theengine for any fraction of a second or for up to several seconds.

Electro-mechanical valve system 76 can also change engine operationbetween fuel sources on-the-fly without gasoline cutoff solenoid 96regulating fuel through liquid fuel line 80. In such an embodiment, uponactuation of switch 54 from gaseous fuel to liquid fuel, carburetorcutoff solenoid 94 can open a liquid fuel path in the carburetor toengage engine operation on liquid fuel and LPG cutoff solenoid 98 canactuate to stop engine operation on gaseous fuel. Also, upon actuationof switch 54 from liquid fuel to gaseous fuel, LPG cutoff solenoid 98can open the gaseous fuel line 84 to engage engine operation on gaseousfuel and carburetor cutoff solenoid 94 can actuate to stop engineoperation on liquid fuel.

Alternatively, electro-mechanical valve system 76 can change engineoperation between fuel sources on-the-fly without carburetor cutoffsolenoid 94. In such an embodiment, gasoline cutoff solenoid 96 can openthe liquid fuel line 80 to engage engine operation on liquid fuel uponactuation of switch 54 from gaseous fuel to liquid fuel, and gasolinecutoff solenoid 96 can stop engine operation on liquid fuel uponactuation of switch 54 from liquid fuel to gaseous fuel. Further,gasoline cutoff solenoid 96 and LPG cutoff solenoid 98 can be preciselytimed to limit or prevent fuel overlap during changeover withoutinterrupting engine performance. For instance, gasoline cutoff solenoid96 may be opened prior to closing LPG cutoff solenoid 98 to ensureadequate fuel in float bowl 88 for on-the-fly changeover. Also, gasolinecutoff solenoid 96 may be closed before LPG cutoff solenoid 98 is openedto reduce fuel in float bowl 88 and limit fuel overlap during on-the-flychangeover. Accordingly, switch 54 may be precisely timed to operategasoline cutoff solenoid 96 and LPG cutoff solenoid 98 to prevent, orsubstantially prevent, simultaneous fuel delivery of the liquid fuel andthe gaseous fuel to the engine.

Referring now to FIG. 3, a schematic diagram of a fuel system to operatethe generator in a tri-fuel arrangement is shown, in accordance with anembodiment of the invention. The fuel system includes anelectro-mechanical valve system 114 coupled to a multi-fuel internalcombustion engine configured to operate on a liquid fuel supplied from aliquid fuel source 78 and first and second gaseous fuels supplied from arespective first gaseous fuel source 116 and second gaseous fuel source118. Electro-mechanical valve system 114 is operated by a tri-fuelelectrical switch 120 that controls fuel flow to the engine from liquidfuel source 78 and gaseous fuel sources 116, 118. In an exemplaryembodiment of the invention, the multi-fuel engine operates on gasolinefrom liquid fuel source 78, liquid petroleum gas (LPG) from firstgaseous fuel source 116, and natural gas (NG) from second gaseous fuelsource 118.

Electro-mechanical valve system 114 may include gasoline cutoff solenoid96 to open and close a liquid fuel path through liquid fuel line 80 tocarburetor 86, a carburetor cutoff solenoid 94 to control liquid fuelflow through the carburetor, and LPG cutoff solenoid 98 to open andclose a gaseous fuel path for the first gaseous fuel through LPG line122 to the engine. Electro-mechanical valve system 114 may also includean NG cutoff solenoid 124, or generally a gaseous fuel cutoff solenoid,to couple the engine intake to second gaseous fuel source 118 and tocontrol flow of the second gaseous fuel to the engine. NG cutoffsolenoid 124 provides a gaseous fuel valve coupled along an NG line 126to open and close second gaseous fuel source 118 to the engine. That is,NG cutoff solenoid 124 operates to open and close a gaseous fuel pathfor the second gaseous fuel through NG line 126 to the engine.

In an exemplary embodiment of the invention, a gaseous fuel line 128provides NG and LPG to the engine by coupling to carburetor 86 and toboth gaseous fuel sources 116, 118. A jet block 80 may be used to couplegaseous fuel line 128 to LPG line 122 and NG line 126. In one embodimentof the invention, jet block 80 is a 2-way branched fitting couplingfirst gaseous fuel source 116 and second gaseous fuel source 118 tocarburetor 86 and located downstream from LPG cutoff solenoid 98 and NGcutoff solenoid 124. Jet block 80 may also comprise a first gaseous fueljet 82 sized for the first gaseous fuel coupled to the first gaseousfuel source 116, and a second gaseous fuel jet 84 sized for the secondgaseous fuel coupled to the second gaseous fuel source 118. The gaseousfuel jets 82, 84 comprise gaseous fuel main jets sized to meter therespective fuels as desired for a particular engine, or based on desiredperformance for each fuel in a given application. Jet block 80 has anoutlet port 86 coupled to gaseous fuel line 128 to provide fuel fromfirst gaseous fuel jet 82 and second gaseous fuel jet 84 to the engine.

Jet block 80 may be used to modify a dual fuel internal combustionengine into a tri-fuel engine by coupling a second gaseous fuel sourceto the engine intake. Jet block 80 can incorporate more than two gaseousfuel jets to couple additional gaseous fuel lines to carburetor 86. Eachfuel line has a gaseous fuel valve to open and close the line. A fuelswitch is wired appropriately to operate the additional solenoids. Assuch, jet block 80 allows a dual fuel engine to operate as a tri-fuelengine, quad-fuel engine or to operate with additional fuel sources.

Electro-mechanical valve system 114 includes a tri-fuel switch 120coupling power source 102 to any of gasoline cutoff solenoid 96, LPGcutoff solenoid 98, NG cutoff solenoid 124, and carburetor cutoffsolenoid 94 to selectively operate the solenoids and engage gasolineoperation when actuated to a first position, engage LPG operation whenactuated to a second position, and engage NG operation when actuated toa third position. When tri-fuel switch 120 engages engine operation onone of the fuels, it may also stop delivery of the remaining fuels tothe engine. As such, solenoids 94, 96, 98, 124 engage engine operationon their respective fuel source upon selection of the tri-fuel switch120 to the respective fuel source, and the solenoids 94, 96, 98, 124stop engine operation on their respective fuel source upon selection ofthe switch to another fuel source.

Electro-mechanical valve system 114 can be configured to switchoperation of the generator from any single fuel to any other single fuelfrom first gaseous fuel source 116, second gaseous fuel source 118, andliquid fuel source 78 on-the-fly while the engine is running. Forinstance, tri-fuel switch 120 can actuate any combination of thecarburetor cutoff solenoid 94, LPG cutoff solenoid 98, NG cutoffsolenoid 124 and gasoline cutoff solenoid 96 to change operation of theengine among the liquid fuel, the first gaseous fuel, and the secondgaseous fuel while the engine remains running. Electro-mechanical valvesystem 114 provides for precisely timed fuel changeover to switch engineoperation among fuel sources with minimal or no interruption in theperformance of the engine, and it can be timed to prevent orsubstantially prevent fuel overlap between the fuel sources.

To change between gaseous fuel and liquid fuel, tri-fuel switch 120 mayoperate NG cutoff solenoid 124 for NG and LPG cutoff solenoid 98 for LPGcorresponding to the description of switch 54 operating LPG cutoffsolenoid 98 with respect to FIG. 2. Referring back to FIG. 3, to switchbetween first gaseous fuel source 116 and second gaseous fuel source118, tri-fuel switch 120 may simultaneously actuate LPG cutoff solenoid98 and NG cutoff solenoid 124 to prevent or substantially preventsimultaneous fuel delivery of first gaseous fuel source 116 and secondgaseous fuel source 118 to the engine. As such, electro-mechanical valvesystem 114 can operate as a tri-fuel lockout to ensure only one fuel isdelivered to the engine. In other embodiments, tri-fuel switch 120actuates the NG cutoff solenoid 124 and LPG cutoff solenoid 98 insuccession to ensure appropriately timed on-the-fly fuel changeoverbetween the two gaseous fuels. Adjustable rheostats or predefinedelectronic delay circuits 108, 110, 112, 88, may be coupled to theelectrical connections of any of solenoids 94, 96, 98, 124, to delaytheir actuation.

In one embodiment of the invention, solenoids 98, 124, 94, 96 operate asnormally closed solenoid valves to ensure excess fuel is not provided tothe engine if power to the solenoids is interrupted. To engage LPGoperation, tri-fuel switch 120 provides electrical connection betweenpower source 102 and first contact 104 to power LPG cutoff solenoid 98to open LPG line 122 while gasoline cutoff solenoid 96, carburetorcutoff solenoid 94, and NG cutoff solenoid 124 are unpowered to closeliquid fuel line 80, the main fuel circuit in carburetor 86, and NG line126, respectively. To engage gasoline operation, tri-fuel switch 120provides electrical connection between power source 102 and secondcontact 106 to power gasoline cutoff solenoid 96 and carburetor cutoffsolenoid 94 to open liquid fuel line 80 and the main fuel circuit incarburetor 86 while LPG cutoff solenoid 98 and NG cutoff solenoid 124are unpowered to close LPG line 122 and NG line 126, respectively. Toengage NG operation, tri-fuel switch 120 provides electrical connectionbetween power source 102 and a third contact 140 to power NG cutoffsolenoid 124 to open NG line 126 while gasoline cutoff solenoid 96,carburetor cutoff solenoid 94 and LPG cutoff solenoid 98 are unpoweredto close liquid fuel line 80, the main fuel circuit in carburetor 86,and LPG line 122, respectively.

In an alternative embodiment of the invention, solenoids 98, 124, 94, 96operate as normally open solenoid valves to ensure fuel is provided tothe engine if power to the solenoids is interrupted. To engage LPGoperation, tri-fuel switch 120 provides electrical connection betweenpower source 102 and both second contact 106 and third contact 140 topower gasoline cutoff solenoid 96, carburetor cutoff solenoid 94, and NGcutoff solenoid 124 to close liquid fuel line 80, main fuel circuit incarburetor 86, and NG line 126, respectively, while LPG cutoff solenoid98 is unpowered to open LPG line 122. To engage gasoline operation,tri-fuel switch 120 provides electrical connection between power source102 and both first contact 104 and third contact 140 to power LPG cutoffsolenoid 98 and NG cutoff solenoid 124 to close LPG line 122 and NG line126 while gasoline cutoff solenoid 96 and carburetor cutoff solenoid 94are unpowered to open liquid fuel line 80 and the main fuel circuit incarburetor 86, respectively. To engage NG operation, tri-fuel switch 120provides electrical connection between power source 102 and both firstcontact 104 and second contact 106 to power gasoline cutoff solenoid 96,carburetor cutoff solenoid 94, and LPG cutoff solenoid 98 to closeliquid fuel line 80, main fuel circuit in carburetor 86, and LPG line122, respectively, while NG cutoff solenoid 124 is unpowered to open NGline 126.

Referring now to FIG. 4, a cross-sectional view of carburetor 86 takentransverse to a barrel or throat 142 of the carburetor is shown, inaccordance with an embodiment of the invention. Fuel and air are mixedin throat 142 to provide an air-fuel mixture for the multi-fuel internalcombustion engine. A butterfly valve 144 is located in throat 142 toprovide a choke and throttle 146 for the engine. Carburetor 86 has afloat bowl 88 to hold liquid fuel with a float valve 148 to control thefuel level in the bowl. Carburetor 86 has a liquid fuel path 150 fromfloat bowl 88 to throat 142. Liquid fuel path 150 is shown in FIG. 4referring to main fuel circuit 152 in carburetor 86, but may alsoinclude other fuel circuits in the carburetor. Main fuel circuit 152provides a flow path from float bowl 88 to a nozzle 154 in a venturi 156upstream from throttle 146. An idle fuel circuit 158 provides a flowpath to the throat 142 downstream of throttle 146 to run the engine atidle.

In one embodiment of the invention, carburetor 86 has a carburetorcutoff solenoid 94 coupled to carburetor 86 to regulate liquid fuel flowto the engine. Carburetor cutoff solenoid 94 actuates to open and closeliquid fuel path 150 to the engine downstream from float bowl 88.Carburetor cutoff solenoid 94 has an actuating member 160 that moves toselectively block fuel flow through liquid fuel path 150, comprisingmain fuel circuit 152, and may be positioned to selectively block fuelflow into the inlet of main fuel circuit 152. Gasoline cutoff solenoid96 (FIG. 2) closes off the liquid fuel line to carburetor 86 and fuelflowing through idle fuel circuit 158 stops when float bowl 88 empties.In another embodiment of the invention, carburetor cutoff solenoid 94 isconfigured to control fuel flow through both main fuel circuit 152 andidle fuel circuit 158. For instance, idle fuel circuit 158 may branchoff from main fuel circuit 152 with carburetor cutoff solenoid 94actuating to block fuel flow into both circuits.

Referring now to FIG. 5, a cross-sectional view of carburetor 86 isshown taken lengthwise to throat 142, in accordance with an embodimentof the invention. Carburetor 86 is attached to the engine at engineintake 162 to supply a metered mixture of air and fuel and connect aliquid fuel source to the intake. Throat 142 includes venturi 156 andthrottle 146 located downstream from venturi 156. A float bowl 88 and afloat 166 control and maintain the fuel level in the bowl from an inletvalve 164. Main fuel circuit 152 provides a flow path from float bowl 88to nozzle 154 in a narrow portion of venturi 156. Idle fuel circuit 158provides a flow path from float bowl 88 to throat 142 downstream ofthrottle 146. Transition fuel circuit 168 provides a flow path to throat142 upstream from throttle 146 and branches off from idle fuel circuit158. Transition fuel circuit 168 is opened to vacuum conditions as thethrottle 146 moves slightly from a closed position to provide additionalfuel as the engine transitions from idle.

Carburetor cutoff solenoid 94 couples to float bowl 88 to selectivelycontrol liquid fuel flow through main fuel circuit 152. Carburetorcutoff solenoid 94 includes actuating member 160 capable of blockingfuel flow through main fuel circuit 152 when actuated. FIG. 5 showsactuating member 160 in an extended or blocking position, while FIG. 4shows actuating member 160 in a retracted or open position. Carburetorcutoff solenoid 94 actuates to quickly start and stop liquid fuel flowfrom float bowl 88 to the engine through main fuel circuit 152 toprovide precisely timed engine changeover between liquid and gaseousfuel sources.

Beneficially, embodiments of the invention thus provide for a multi-fuelinternal combustion engine capable of switching between liquid fuel andgaseous fuel sources while the engine is running. Embodiments of theinvention also provide for a multi-fuel internal combustion enginehaving a fuel system to prevent an overly rich air-fuel ratio duringcross-over switching between fuel sources. Embodiments of the inventionalso provide for a multi-fuel generator with a remotely mounted gaseousfuel pressure regulator system.

Therefore, according to one embodiment of the invention, a multi-fuelengine includes an engine operable on a liquid fuel, a first gaseousfuel from a first gaseous fuel source, and a second gaseous fuel from asecond gaseous fuel source. The multi-fuel engine also includes a liquidcutoff solenoid coupled to open and close a liquid fuel path to theengine, a first gaseous cutoff solenoid coupled to open and close thefirst gaseous fuel source to the engine, a second gaseous cutoffsolenoid coupling the engine to the second gaseous fuel source tocontrol flow of the second gaseous fuel to the engine, and a switchcoupling a power source to the liquid cutoff solenoid and the firstgaseous cutoff solenoid to switch between fuel sources on-the-fly duringengine operation.

According to another embodiment of the invention, a multi-fuel engineincludes an engine operable on a liquid fuel, a first gaseous fuel froma first gaseous fuel source, and a second gaseous fuel from a secondgaseous fuel source. The multi-fuel engine also includes a liquid cutoffsolenoid selectively operable between open and closed positions to allowand inhibit a flow of the liquid fuel to the engine, at least onegaseous cutoff valve selectively operable between open and closedpositions to allow and inhibit a flow of the first gaseous fuel and thesecond gaseous fuel to the engine. and a jet block coupling the firstgaseous fuel source and the second gaseous fuel source to a carburetorconnected to an intake of the engine, wherein the jet block is locateddownstream from the at least one gaseous cutoff valve. The jet blockfurther includes a first gaseous fuel jet configured to meter the firstgaseous fuel to the carburetor and a second gaseous fuel jet configuredto meter the second gaseous fuel to the carburetor.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A multi-fuel engine comprising: an engineoperable on a liquid fuel and a gaseous fuel; a carburetor attached toan intake of the engine to mix air and fuel and connect a liquid fuelsource to the intake, the carburetor comprising a float bowl; a liquidcutoff solenoid coupled to open and close a liquid fuel path to theengine; a gaseous cutoff solenoid coupled to open and close a gaseousfuel source to the engine; a switch selectively coupling a power sourceto the liquid cutoff solenoid and the gaseous cutoff solenoid to openand close the liquid fuel path and the gaseous fuel path; and one ormore timing circuits electrically coupled to the liquid cutoff solenoidand the gaseous cutoff solenoid that operate to control an actuationtime of the liquid cutoff solenoid and the gaseous cutoff solenoid. 2.The multi-fuel engine of claim 1 wherein the one or more timing circuitscomprise one or more delay circuits configured to institute a predefineddelay before actuating the liquid cutoff solenoid and the gaseous fuelcutoff solenoid.
 3. The multi-fuel engine of claim 1 wherein the one ormore timing circuits comprise one or more rheostats configured toinstitute a delay before actuating the liquid cutoff solenoid and thegaseous fuel cutoff solenoid.
 4. The multi-fuel engine of claim 1wherein the one or more timing circuits provide a user adjustable presetdelay before actuating the liquid cutoff solenoid and the gaseous cutoffsolenoid.
 5. The multi-fuel engine of claim 1 wherein the one or moretiming circuits control the actuation time of the liquid cutoff solenoidand the gaseous cutoff solenoid to provide simultaneous delivery offuels to the engine for any fraction of a second or for up to severalseconds.
 6. The multi-fuel engine of claim 1 wherein the switch and theone or more timing circuits control actuation of the liquid cutoffsolenoid and the gaseous cutoff solenoid to enable changing engineoperation between the liquid fuel and the gaseous fuel, so as to preventfuel flow from the liquid fuel source and the gaseous fuel sourcesimultaneously and allow switching between fuel sources on-the-flyduring engine operation.
 7. The multi-fuel engine of claim 1 wherein theliquid cutoff solenoid comprises a first liquid cutoff solenoid coupledto the carburetor to control flow of liquid fuel within the carburetor,and wherein the multi-fuel engine further comprises a second liquidcutoff solenoid positioned on a liquid fuel line coupling the liquidfuel source to the carburetor to open and close the liquid fuel sourceto the engine.
 8. The multi-fuel engine of claim 7 wherein one of theone or more timing circuits is electrically coupled to the second liquidcutoff solenoid to control an actuation time of the second liquid cutoffsolenoid, such that the actuation time of the second liquid cutoffsolenoid is controlled along with the actuation time of the first liquidcutoff solenoid and the gaseous cutoff solenoid.
 9. The multi-fuelengine of claim 1 wherein the engine is a dual fuel engine that operateson gasoline from the liquid fuel source and LPG from the gaseous fuelsource.
 10. The multi-fuel engine of claim 1 wherein the carburetorconnects the gaseous fuel source to the intake.
 11. The multi-fuelengine of claim 1 further comprising: an alternator driven by the engineto form a generator; and a fuel regulator system located off-board thegenerator and comprising: a primary pressure regulator coupled to aservice valve of the pressurized fuel source to regulate the fuelsupplied from the pressurized fuel source to a reduced pressure, and asecondary pressure regulator coupled to the primary pressure regulatorto regulate the gaseous fuel supplied from the primary pressureregulator to a desired pressure for delivery through the gaseous fuelline to operate the engine.
 12. A multi-fuel generator and fuel deliverysystem comprising: a multi-fuel internal combustion engine configured tooperate on a liquid fuel supplied from a liquid fuel source through aliquid fuel line and a gaseous fuel supplied from a pressurized fuelsource through a gaseous fuel line; an alternator driven by themulti-fuel internal combustion engine; and a fuel regulator systemcomprising: a primary pressure regulator coupled to a service valve ofthe pressurized fuel source to regulate fuel supplied from thepressurized fuel source to a reduced pressure, and a secondary pressureregulator coupled to the primary pressure regulator to regulate fuelsupplied from the primary pressure regulator to a desired pressure fordelivery through the gaseous fuel line to operate the engine.
 13. Themulti-fuel generator and fuel delivery system of claim 12 anelectro-mechanical valve system coupled to the engine and operated by anelectrical switch powered by one of the alternator, a battery, and amagneto that controls fuel flow to the engine from the liquid fuelsource and the pressurized fuel source.
 14. The multi-fuel generator andfuel delivery system of claim 13 wherein the electro-mechanical valvesystem is configured to switch operation of the generator from multiplefuel sources while the generator is running.
 15. The multi-fuelgenerator and fuel delivery system of claim 13 wherein theelectro-mechanical valve system is configured to prevent simultaneousdelivery of the liquid fuel and the gaseous fuel to the engine.
 16. Themulti-fuel generator and fuel delivery system of claim 12 wherein thepressurized fuel source comprises a pressurized fuel container locatedoff-board the generator having a regulator mounting device to secure atleast the secondary pressure regulator thereto.
 17. The multi-fuelgenerator and fuel delivery system of claim 12 wherein a dual stagepressure regulator comprises the primary pressure regulator and thesecondary pressure regulator.
 18. A carburetor for use in a multi-fuelinternal combustion engine, the carburetor comprising: a throat in whichfuel and air are mixed in throat to provide an air-fuel mixture for themulti-fuel internal combustion engine; a valve located in the throat toprovide a choke and throttle for the multi-fuel internal combustionengine; a float bowl to hold liquid fuel; a main fuel circuit positioneddownstream from the float bowl and extending from the float bowl to thethroat; an idle fuel circuit that provides a flow path to the throatdownstream of the throttle to run the engine at idle; and a carburetorcutoff solenoid configured to selectively control fuel flow through themain fuel circuit and the idle fuel circuit.
 19. The carburetor of claim18 wherein the carburetor cutoff solenoid is operatively coupled to aswitch that changes operation of the engine from liquid fuel to gaseousfuel and from gaseous fuel to liquid fuel while the engine is running,and wherein the carburetor cutoff solenoid is closed to stop liquid fuelflow through the main fuel circuit and the idle fuel circuit when theswitch changes operation of the engine from liquid fuel to gaseous fuel.